The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Traditionally, vehicles include a prime mover, such as an internal combustion engine, that generates drive torque. The drive torque is transferred through a powertrain to drive a drivetrain, propelling the vehicle along a surface. Exemplary powertrain components include a transmission and a coupling device, through which the drive torque from the engine is transferred to the transmission. The transmission multiplies the drive torque by a gear ratio and further transfers the multiplied drive torque to the driveline.
An exemplary transmission includes an automatic transmission having a plurality of transmission elements that are hydraulically engaged to establish a desired gear ratio. Accordingly, each transmission element includes a corresponding hydraulic circuit having a variable bleed solenoid (VBS) to regulate the actuation pressure of a corresponding transmission element.
A transmission slip condition can occur when a transmission element is defective and/or worn or the corresponding hydraulic circuit is providing insufficient pressure to fully engage the particular transmission element. The transmission slip condition can damage transmission components and detrimentally affects the vehicle drivability.
Accordingly, traditional transmission slip control routines determine whether a slip condition is present and commands a transmission shift if the slip condition remains for a predetermined time period. By executing a shift and monitoring whether a slip condition exists in the next gear ratio, the traditional transmission slip control can identify which transmission element and/or hydraulic circuit is the source of the slip condition. However, if the vehicle operator changes the vehicle operating conditions (e.g., steps into the accelerator pedal changing the engine torque request), another transmission shift may be executed. As a result, the traditional slip control can inaccurately identify a particular transmission element and/or hydraulic circuit as being defective, which results in increased warranty costs and customer dissatisfaction.